The influence of two home-applied bleaching agents on enamel microhardness: An in situ study

• Published in: Journal of dentistry Vol. 36; no. 1; pp. 2 - 7
• Main Authors: Maia, Elaine, Baratieri, Luiz Narciso, Andrada, Mauro Amaral Caldeira de, Monteiro, Sylvio, Vieira, Luiz Clóvis Cardoso
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.01.2008; Elsevier Limited
• Subjects: Adult; Analysis of Variance; Aqueous solutions; Bleaching agents; Carbamide peroxide; Case-Control Studies; Dental Enamel - chemistry; Dental Enamel - drug effects; Dentistry; Drug Combinations; Enamel; Enamel microhardness; Female; Hardness - drug effects; Home bleaching; Humans; Hydrogen peroxide; Hydrogen Peroxide - adverse effects; Hydrogen Peroxide - pharmacology; Hypotheses; In situ study; Male; Microhardness; Oxidants - adverse effects; Oxidants - pharmacology; Peroxides - adverse effects; Peroxides - pharmacology; Studies; Tooth Bleaching - methods; Urea - adverse effects; Urea - analogs & derivatives; Urea - pharmacology; Volunteers; Bleaching agents; Hydrogen peroxide; Enamel microhardness; Home bleaching; In situ study; Carbamide peroxide
• ISSN: 0300-5712; 1879-176X
• DOI: 10.1016/j.jdent.2007.09.011

Abstract Objective This in situ study evaluated the influence of two home-applied bleaching agents (10% carbamide peroxide and 7.5% hydrogen peroxide) on enamel microhardness. Methods Ninety enamel slabs were obtained from human third molars and baseline Knoop hardness measurements were recorded under a 50 g load for 5 s. The specimens were attached to intra-oral devices delivered to 10 volunteers (donor of the teeth) who used the devices 24 h/day throughout the experiment. The specimens were divided in three groups, two experimental and one control; in the last group, enamel slabs were not submitted to bleaching agents, but exposed only to the action of saliva. Two custom-made trays were made for each volunteer to recover the teeth and the appliances containing the enamel slabs. The bleaching regimen was 1 h/day for 21 consecutive days. Subsequently, additional hardness measurements were recorded. Results The mean values of the baseline and final microhardness were: 348 and 352.2; 346.6 and 354.5; 342 and 340.8, for control, 10% carbamide peroxide and 7.5% hydrogen peroxide groups, respectively. One-way ANOVA of the microhardness mean values revealed no statistically significant differences among groups, the specimens treated with 7.5% hydrogen peroxide has shown a tendency ( p = 0.056) to microhardness decrease. Conclusions Data suggested that the tested home bleaching agents did not change the superficial enamel microhardness.